Photographic diffusion transfer product and process

ABSTRACT

A substantially protein free receiving layer for use in a photographic diffusion transfer process comprises silver precipitants and a colloid binder comprising at least 90 percent, by weight, of a copolymer of (1) about 90 percent to about 98 percent, by weight, of at least one haloalkyl methacrylate in which the haloalkyl group contains 1 to 10 carbon atoms with (2) about 2 percent to about 10 percent, by weight, of an unsaturated polymerizable organic acid having three to six carbon atoms. The layer can also contain toning and/or processing compounds.

United States Patent l 13,632,338

[72] Inventors Dorothy J. Beavers [56] References Clted mf d mm d UNITED STATES PATENTS 3,234,022 2/1966 Land et al 96/29 [2 App! No 5 33?; pemmchemmu 3,260,600 7/1966 De Haes 96/29 x [22] Filed Feb. 1969 3,493,550 2/1970 Schmrtt 260/86.] [45] Patented Jan. 4, 1972 Primary Examiner-Norman G. Torchin [73] Assignee Ea tman Kod k Co Assistant Examiner.lohn L. Goodrow Ro he t r, N Y Attorneys-W. H. J. Kline, B. D. Wiese and H. E. Byers [54] Pl-lOTOGRAPl-IIC DIFFUSION TRANSFER ABSTRACT: A substantially protein free receiving layer for PRODUCT AND PROCESS use in a photographic diffusion transfer process comprises 17 Cl i No D i silver precipitants and a colloid binder comprising at least 90 percent, by weight, of a copolymer of I) about 90 percent to 603921;: about 98 percent by weight of at least one haloalkyl [so] i 96/2; methacrylate in which the haloalkyl group contains 1 to 10 carbon atoms with (2) about 2 percent to about 10 percent, by weight, of an unsaturated polymerizable organic acid having three to six carbon atoms. The layer can also contain toning and/or processing compounds.

PI'IOTOGRAPIIIC DIFFUSION TRANSFER PRODUCT AND PROCESS BACKGROUND OF THE INVENTION This invention relates to polymeric colloid binders for silver precipitants used in diffusion transfer products and processes.

Diffusion transfer processes are well known. For example, Rott, US. Pat. No. 2,352,0l4 describes such a process wherein undeveloped silver halide of an exposed photographic emulsion layer is transferred in a silver complex imagewise by imbibition to a silver precipitating layer, generally to form a positive image therein. The silver precipitating layer generally comprises a binder containing silver precipitant, e.g., nuclei such as nickel sulfide, colloidal metal or the like.

In carrying out the diffusion transfer process, there have been many problems involved in obtaining a satisfactory image. For instance, many of the prints have a brownish image, lack stability, show objectionable stain, etc. Therefore, various methods have been proposed to improve the process such as incorporation of toning agents in the processing solution, substitution of various silver precipitants, the use of water impervious layers to preclude absorption therein or into the receiving sheet of processing chemicals, oxidized developer, etc.

In order to form a water impervious coating on the paper receiving sheet, it has been customary to use a polymeric layer which is deposited on the paper support. The water impervious layer prevents aqueous processing solutions, such as fixing baths, silver halide developing baths, or the like, from penetrating into the paper support where they cause stain. Over the polymeric layer, silver precipitating nuclei are deposited, usually in a colloid binder such as gelatin, etc. However, using gelatin as a vehicle for silver precipitants such as nuclei, especially with certain types of nuclei such as colloidal silver, results in prints having a yellow or light brown color. The problem of obtaining a desirable tone using a gelatin binder has been recognized in the art and various attempts have been made to overcome this problem, as can be seen by Land et al., US. Pat. No. 2,774,667 issued Dec. 18, 1956, which describes the use of a silica matrix for silver precipitating nuclei such as colloidal silver to avoid having the prints result in a yellow or light brown color.

It has also been proposed to use a polymeric binder for nuclei in order to provide a water impervious coating on the support. Polymers can be applied to a support by two well known methods. For instance, a polymer can be dissolved in a volatile organic solvent to provide a suitable coating composition which is then coated on the support and the solvent allowed to evaporate to form a coating layer. In this type of coating, the nuclei are effectively isolated from an aqueous solutions so that they can not effectively perform their function of acting as sites for precipitating silver from the silver complex. Therefore, this method of applying the nuclei to a surface is unsatisfactory.

Another method of applying a polymer to a surface is to apply the polymer as a latex, preferably an aqueous latex. Certain latex coating compositions containing nuclei can be used to form a water-resistant layer on a paper support which decreases the amount of strain which is obtained. If the coating is desired to be completely impervious to water, a coalescing step is required, usually requiring heat, in which the particles of the latex are coalesced to form a water impervious layer. This type of treatment tends to shield the nuclei from the complexed silver and also produces unsatisfactory results. In addition, it has been found that many polymeric binders, particularly the hydrophilic colloid binders, also result in yellow or light brown images.

It is recognized that a binder which would behave satisfactorily when used with silver precipitants such as nuclei to form a receiving layer would be very useful in diffusion transfer processes if it would result in a neutral or black image. It is also recognized that it would be desirable to obtain a binder which would provide a water resistant layer on a paper support in order to reduce stain from penetration of processing chemicals into the base support.

SUMMARY OF THE INVENTION In accordance with this invention, it has been found that hydrophobic polymers, as described herein, can be used in diffusion transfer processes as binder for a silver precipitant such as nuclei to overcome several of the disadvantages described hereinbefore. These polymers are conveniently used in a latex form and provide a substantially protein free receiving layer having the desired image forming properties. Useful binders comprise at least about percent, preferably at least about percent, by weight, of a copolymer of l about 90 percent to about 98 percent, by weight, of at least one haloalkyl methacrylate in which the haloalkyl group contains one to 10 carbon atoms with (2) about 2 to about 10 percent, by weight, of an ethylenically unsaturated polymerizable organic acid having three to six carbon atoms.

In a particularly useful embodiment, the polymeric latex employed in the practice of this invention is used as a binder with noble metal nuclei as described in US. Pat. application entitled Photographic Diffusion Transfer Product and Process," Ser. No. 796,552 filed concurrently herewith in the name of Rasch.

A receiving element as described above is used advantageously to provide a photographic print having an image in a receiving layer on a support. The image is obtained by the photographic silver salt diffusion transfer process and is formed in a receiving layer which comprises a colloid binder, as described herein, and suitable silver precipitating agents.

DESCRIPTION OF PREFERRED EMBODIMENTS A significant feature of this invention is that the binder is substantially protein free. As can be seen from example 4 herein, the presence of a small amount of protein in the binder results in a warm tone. Another significant feature of this invention is the use of a latex binder comprising a copolymer of haloalkyl methacrylate and acrylic acid. As can be seen from example 5, hereinafter described, the use of polymers containing three components or of copolymers containing other acrylates than the haloalkyl methacrylate results in a density which is unsatisfactory.

In one embodiment of this invention, colloidal noble metal nuclei are dispersed in a latex such as a copoly( 2-chloroethyl methacrylate-acrylic acid) (98:2 weight percent) latex after which the latex is coated on a suitable support such as paper. After drying, the receiving sheet can then be used in diffusion transfer process and provides a surface substantially resistant to penetration by the processing solution, but which enables the nuclei to be accessible to complexed silver halide so that an image can be formed.

In another embodiment of this invention, colloidal nuclei are dispersed in a latex binder, as described herein, and the latex-nuclei composition coated on a suitable support such as paper. After drying, an unhardened silver halide emulsion is coated over the nuclei layer. Particularly useful emulsions are described in Yackel et al., US. Pat. No. 3,020,155. The exposed photographic element is processed using a silver halide developing solution containing a silver halide solvent such as sodium thiosulfate. The undeveloped silver halide, complexed with the thiosulfate, diffuses to the nucleated underlayer where an image is formed which is positive with respect to the negative image formed in the silver halide emulsionv The unhardened silver halide emulsion is then removed by washing with warm water.

The binder for the nuclei is substantially protein free and comprises at least about 90 percent, by weight, of a copolymer as described herein. The polymers particularly useful in carrying out our invention can be characterized as water-insoluble, linear addition copolymers of a haloalkyl methacrylate with an ehylenically unsaturated polymerizable organic acid having three to six carbon atoms.

Copolymers which are particularly useful in carrying out our invention can be prepared by copolymerizing by known methods a mixture of monomers comprising a haloalkyl methacrylate, particularly a mono haloalkyl methacrylate.-

such as, for example, chloro alkyl methacrylate, bromo alkyl methacrylate, fluoro alkyl acrylate or iodo alkyl methacrylate, in which the haloalkyl group has from one to carbon atoms, preferably one to four carbon atoms, e.g., .methyl, ethyl, propyl or butyl, and an ethylenically unsaturated polymerizable organic acid monomer such as, for example, acrylic acid, methacrylic acid, itaconic acid, etc. The unsaturated acid component of the mixture can be from 2 to about 10 percent, by weight, but preferably from about 2 to about 6 percent, by weight. Typically the copolymer has a molecular weight of about 7,500 to about 250,000. The copolymerization can, for example, be conducted in an aqueous emulsion containing the monomers, a catalyst and activator, and an emulsifying and/or dispersing agent. The total catalyst concentration should be kept within the range of 0.1 to 1.0 percent, by weight, of the monomer charge.

2-chloroethyl methacrylate can be prepared in any convenient manner. For example, it can be prepared from a mixture of benzene, methacrylic acid (20 moles), ethylene chlorohydrin (20 moles), p-toluene sulfonic acid (100 g.) and an inhibitor such as hydroquinone or methylhydroquinone (100 g.) The mixture is heated until azeotropic distillation of water ceases. The reaction mixture is then cooled, the benzene removed under reduced pressure at low temperature and the crude product is distilled in vacuo to obtain 2- chloroethyl methacrylate. Other haloalkyl methacrylates are prepared in a similar manner.

A copolymer of 2-chloroethyl methacrylate with acrylic acid is prepared from a mixture of 2-chloroethyl methacrylate, acrylic acid, a wetting agent, potassium persulfate and potassium metabisulfate. The mixture is placed in a 1 quart bottle, the bottle flushed with nitrogen, capped and tumbled at rpm, end over end, in a 40 C. water bath for 16 hours. The resulting mixture is cooled to room temperature and filtered to obtain a copolymer latex.

Hydrophobic polymers are usually prepared with about 2 to about 4 percent surfactant, by weight, of the solvents present in the polymerization reaction mixture. However, the polymers for use in the layers of our invention are found to be improved with respect to characteristics such as stability on incubation, latitude in curing the latex when used as a binder on a receiving sheet, and the like, by lowering this level of surfactant. The surfactant concentration is reduced from about 2 percent to below about 1 percent, by weight, of the solvents present and the revolutions per minute of the mixer used to agitate the reaction mixture during polymerization is increased to a range of from about 800 to about 1,750.

Latex coating solutions which contain addenda other than silver precipitant are also useful. In addition to various nuclei contained in the latex, toners, surfactants, coating aids, developing agents, stripping agents, silver halide solvents, etc., can be added to improve the image quality in the receiving sheet.

Particularly useful surfactants and spreading agents in latex coatings include saponin, lauryl alcohol sulfate, p-tertoctyl phenoxy ethoxy ethyl sodium sulfonate, etc.

Latex formulations as described herein can also be improved by using thickeners in dispersions of the nuclei in latex. A particularly useful thickener is a polysaccharide gum as described in U.S. Pat. No. 3,000,790 issued Sept. 19, 1961 to Jeanes et al. Other well known thickeners such as colloidal hydrated aluminum silicate, colloidal silica, magnesium mortmorillonite clay, attapulgite clay, talc, sodium silica aluminate, etc., may also be used. The concentration of thickener which is used, of course, depends upon the preferred viscosity of the coating composition. In a typical method of preparation, the nuclei latex mixture is prepared and the thickener added to it to obtain the desired viscosity.

Suitable silver precipitants for use in the receiving layer include various silver precipitating agents known in the art. As examples of suitable silver precipitating agents, and of imagereceiving elements containing such silver precipitating agents, reference may be made to U.S. Pat. Nos. 2,698,237, 2,698,238 and 2,698,245 issued to Edwin H. Land on Dec. 28, 1954, U.S. Pat. No. 2,774,667 issued to Edwin H. Land and Meroe M. Morse on Dec. 18, 1956, U.S. Pat. No. 2,823,122 issued to Edwin H. Land on Feb. 11, 1958, U.S. Pat. No. 3,396,018 issued to Beavers et al. Aug. 6, 1968 and also U.S. Pat. No. 3,369,901 issued to Fogg et al. Feb. 20, 1968. The noble metals, silver, gold, platinum, palladium, etc., in the colloidal form are particularly useful.

Noble metal nuclei are particularly active and useful when formed by reducing a noble metal salt using a borohydride or hypophosphite in the presence of a colloid as described in the above concurrently filed Rasch application. The metal nuclei are prepared in the presence of a latex as described in herein and coated on the receiving sheet. It will be appreciated from the above, that the coating composition generally contains not only nuclei, but also reaction products which are obtained from reducing the metal salt. Accordingly, it is within the scope of our invention to include in the receiving layer the reaction by-products which are obtained during the reducing operation.

The amount of colloid used in preparing the above active noble metal nuclei can be varied depending upon the particular colloid, reducing agent, ratio or proportions, etc. Typically about 0.5 percent to about 20 percent, by weight, based on the total reaction mixture of colloid is used, preferably from about 1 percent to about 10 percent.

In a particularly useful embodiment, 14 micrograms of the above active noble metal nuclei in milligrams of latex (solids basis) is coated per square foot of support. The colloid binder is advantageously coated in a range of about 5 to about 500 mg./ft. Suitable concentrations on the receiving sheets of active noble metal nuclei as disclosed above can be about 1 to about 200 Lg/ft. Other silver precipitants can be coated in a concentration of up to 5 mg./ft.

The supports which can be used for coating with the receiving layer are any of those which are suitable and include paper, wood, glass, plastics, etc. A particularly useful support is paper, especially baryta coated paper. However, in a preferred embodiment, a polymeric material which acts as a moisture barrier, such as polyethylene or the like, which is pigmented to provide a white surface is used. Antistain agents, such as acids, etc., can be incorporated in the supports or supporting layers. Typical antistain agents are disclosed in Youngkurth et al., U.S. Pat. No. 3,250,619 and Youngkurth U.S. Pat. No. 3,326,744. Other polymeric materials which may be used as coatings on paper or as self-supported webs include polyesters, polyamides, polycarbonates, polyolefms, cellulose esters, polyacetals and the like.

In order to obtain adhesion or to improve adhesion to a receiving support, treatments of the support, e.g., photographic fllm base, may be carried out including subbing the support, electron bombardment, treating with peroxide and the like.

The nuclei can be formed in situ by coating a layer of nuclei precursor such as a metal salt in a latex on a support and overcoating with a layer of a suitable reactant such as a reducing agent. For example a coating containing latex and gold chloride can be coated on a suitable support over which is then coated a layer containing sodium borohydride. Similarly, nickel chloride can be reacted with sodium sulfide in situ, for example, to form nickel sulfide nuclei.

Toning agents are generally present during the diffusion transfer step. For example, the receiving sheet can contain various toning agents or toning agents can be in the processing solution or even, in some instances, contained in the silver halide emulsion. Toning agents which can be included for improving the tone of the image to make the tone blacker or more blue-black include sulfur compounds such as 2-mercaptothiazoline, 2-amino-5-mercapto-1,3,4-thiadiazole, 2- thionoimidazoline, 2-mercapto-S-methyloxazoline and 2- thionoimidazolyne. These toners are particularly useful in a range of 0.01 to 3.0 mg./ft. either in the receiving layer or coated in a layer on top of the nucleated layer. It will be appreciated that these toners can be used either alone or in conjunction with other toning agents. Other toning agents which can be used include the S-mercaptotetrazoles of Abbott et al., U.S. Pat. No. 3,295,971 and Weyde, U.S. Pat. No. 2,699,393. Still other toning agents are disclosed in Tregillus et al., U.S. Pat. No. 3,017,270.

The receiving layers of our invention can have therein particles such as silica, bentonite, diatomaceous earth such as Kieselguhr, powdered glass and fullers earth. ln addition, colloids and colloidal particles of metal oxides such as titanium dioxide, colloidal alumina, coarse aluminum oxide, zirconium oxide and the like can be used with the nuclei in the receiving layers.

In carrying out the diffusion transfer process, conventionally a silver halide emulsion is exposed to a light image after which it is contacted with a silver halide developing agent containing a silver halide complexing agent. The exposed emulsion is developed in the light struck areas and the unexposed silver halide is complexed with the silver halide complexing agent, after which the emulsion is contacted against a receiving sheet and the complex silver halide diffuses imagewise to the receiving sheet containing nuclei.

In some instances it may be desirable to treat the receiving sheet in order to improve the stability of the sheet, particularly with regard to the silver image thereon. A simple stabilizing method merely involves washing the print in order to remove any processing chemicals which may remain thereon. How ever, the washing step does not protect the print from subsequent chemical reactions with oxygen, hydrogen sulfide, etc., in the atmosphere, which have an adverse effect on the stability of the silver image. For these reasons, it has been proposed to coat the print with a coating composition such as that disclosed in U.S. Pat. No. 2,979,477 comprising a mixture of vinylpyridine polymer and a hydantoin-formaldehyde condensation polymer.

Suitable print coating compositions can also employ a polymeric material such as a methylmethacrylate-methacrylic acid copolymer or the combination of an acid group or sulfate group containing polymer such as copoly(methylmethacrylate-methacrylic acid) and a hydantoin-formaldehyde condensation polymer, such as that disclosed in French Pat. No. 1,493,188. A heavy metal salt such as zinc acetate may also advantageously be incorporated in the print coating composition. Further improvement is obtained by incorporating in the coating composition an acid, such as acetic acid, propionic acid or the like.

Silver halide developing agents or developing agent precursors used for initiating development of the exposed sensitive element can be conventional types used for developing films or papers with the exception that a silver halide solvent or complexing agent, such as sodium thiosulfate, sodium thiocyanate, ammonia or the like, is present in the quantity required to form a soluble silver complex which diffuses imagewise to the receiving support. Usually, the concentration of developing agent and/or developing agent precursor employed is about3 to about 320 mg./ft. of support.

Developing agents and/or developing agent precursors can be employed in a viscous processing composition containing a thickener such as carboxymethyl cellulose or hydroxyethyl cellulose. A typical developer composition is disclosed in U.S. Pat. No. 3,120,795 ofLand et al. issued Feb. 11, 1964.

Developing agents and/or developing agent precursors can be employed alone or in combination with each other, as well as with auxiliary developing agents. Suitable silver halide developing agents and developing agent precursors which can be employed include, for example, polyhydroxybenzenes, such as hydroquinone developing agents, e.g., hydroquinone, alkyl substituted hydroquinones, as exemplified by t-butyl hydroquinone, methyl hydroquinone and 2,5-dimethylhydroquinone, catechol and pyrogallol; chloro substituted hydroquinones such as chlorohydroquinone or dichlorohydroquinone; alkoxy substituted hydroquinones such as methoxy hydroquinone or ethoxy hydroquinone; aminophenol developing agents such as 2,4-diaminophenols and methylaminophenols. These include, for example, 2,4- diaminophenol developing agents which contain a group in the 6 position, and related amino developing agents, e.g.,

6-methyl-2,4-diaminophenol 6-methoxy-2,4-diaminophenol 6-ethyl-2,4diaminophenol 6-phenyl-2,4-diaminophenol 6-para tolyl-2,4-diaminophenol 6-chloro-2,4-diaminophenol 6-morpholinomethyl-Z,4-diaminophenol 6-piperidino-2,4-diaminophenol 3,6-dimethyl-2,4-diaminophenol 6-phenoxy-2,4-diaminophenol 2-methoxy-4-amino-5-methyl phenol 4-aminocatechol 4-aminorescorcinol 2,4-diaminorescorcinol methyl-3,4-diaminophenol methoxy-3,4-diaminophenol methyl-2,5-diaminophenol methoxy-2,5-diaminophenol methyl-1,2,4-triamino benzene methoxyl ,2,4-triamino benzene p-hydroxyphenyl hydrazine p-hydroxyphenyl hydroxylamine The aminophenol developing agents can be employed as an acid salt, such as a hydrochloride or sulfate salt.

Other silver halide developing agents include ascorbic acid, ascorbic acid ketals, such as those described in U.S. Pat. No. 3,337,342 of Green issued Aug. 22, 1967; hydroxylamines such as N,N-di(2-ethoxyethyl)hydroxylamine; 3-pyrazolidone developing agents such as l-phenyl-3-pyrazolidone, including those described in Kodak British Pat. No. 930,572 published July 3, 1963; and acyl derivatives of p-aminophenol such as described in Kodak British Pat. No. 1,045,303 published Oct. 12, 1966.

Lactone derivative silver halide developing agents which have the property of forming a lactone silver halide developing agent precursor under neutral and acid conditions are particularly useful. The particularly suitable lactone derivatives provide desired developing activity and reduction of stain without adversely affecting desired maximum density, minimum density, photographic speed and other desired sensitometric properties. Suitable lactone derivative developing agents include those which under neutral, slightly alkaline or acid conditions, i.e., when the pH is lowered to a level of about 9 or lower, i.e., about 2 to about 9, do not have significant developing activity, if any, due to formation of a developing agent precursor.

Silver halide emulsions employed with receiving layers and elements of this invention can contain incorporated addenda, including chemical sensitizing and spectral sensitizing agents, coating agents, antifoggants and the like, They can also contain processing agents such as silver halide developing agents and/or developing agent precursors. Of course, the processing agents can be incorporated in a layer adjacent to the silver halide emulsion if desired.

The photographic emulsions employed can also be X-ray or other nonspectrally sensitized emulsions or they can contain spectral sensitizing dyes such as described in U.S. Pat. Nos. 2,526,632 of Brooker et al. issued Oct. 24, 1950 and 2,503,776 of Sprague issued Apr. 11, 1950. Spectral sensitizers which can be used include cyanines, merocyanines, styryls and hemicyanines.

The photographic emulsions can contain various photographic addenda, particularly those known to be beneficial in photographic compositions. Various addenda and concentrations to be employed can be determined by those skilled in the art. Suitable photographic addenda include hardeners, e.g., those set forth in British Pat. No. 974,317; buffers which maintain the desired developing activity and/or pH level; coating aids; plasticizers, speed increasing addenda, such as amines, quaternary ammonium salts, sulfonium salts and alkylene oxide polymers; and various stabilizing agents, such as sodium sulfite. The photographic silver slat emulsions can be chemically sensitized with compounds of the sulfur group such as sulfur, selenium and tellurium sensitizers, noble metal salts such as gold, or reduction sensitized with reducing agents or combinations of such materials.

Various photographic silver salts can be used in the practice of the invention. These include photographic silver halides such as silver iodide, silver bromide, silver chloride, as well as mixed halides such as silver bromoiodide, silver chloroiodide, silver chlorobromide and silver bromochloroiodide. Photographic silver salts which are not silver halides can also be employed such as silver salts of certain organic acids such as silver-dye salts, etc.

The photographic silver salts are typically contained in an emulsion layer comprising any binding materials suitable for photographic purposes. These include natural and synthetic binding materials generally employed for this purpose, for example, gelatin, colloidal albumin, water-soluble vinyl polymers, mono and polysaccharides, cellulose derivatives, proteins, water-soluble polyacrylamides, polyvinyl pyrrolidone and the like, as well as mixtures of such binding agents. The elements can also contain stripping layers and/or antistatic layers.

Stripping agents can be used either on the surface of the silver halide emulsion layer, on the receiving layer containing the nuclei, or can be contained in the developing or processing solutions. When added to the processing solution in concentrations of about 3 percent to about 10 percent, by weight, the stripping agents prevent the processing solution from sticking to the receiver. Suitable stripping agents normally are used which have a composition different from the binder used in the silver halide emulsion. These coatings are relatively thin having a preferred coverage of about 6.0 mg./ft. However, a useful range may be from 1.0 mg. to 1.0 g./ft. It will also be understood that a stripping agent or release agent can be incorporated in the receiving layer along with the nuclei and/or binder used as a carrier for the nuclei.

The following examples are included for a further understanding of the invention:

EXAMPLE l Latex Mixture Solution A Water 657 ml. 20% Latcx-copoly(2-chloroethyl 35 ml. methacrylate-acrylic acid) 96% Z-chloroethyl methacrylatc- 4% acrylic acid, by weight 20% Latcx-copoly(butyl acrylate- 3.55 ml. acrylic acid) 90% butyl acrylatel% acrylic acid, by weight l5% Saponin solution 5.0 ml.

To 100 ml. portions of Solution A are added (l) 2.50 ml. of palladium chloride solution at 1.25 mg./ml. of solution; (2) 5.0 ml. of NaBH, reducing agent solution mg./ml.) and (3) distilled water to bring the total volume of each solution of 1 18 ml.

The samples are held for 30 minutes at 70 C. All of the solutions are then coated at 0.002 inch on a polyethylene coated paper support to give a nuclei coverage of about 75 pg/ft. and about 80 mg./ft. of latex (solids). All of the coatings are made at l00 F. and cured at 205 F. for l minute. The receiving sheet is used in a photographic silver salt diffusion transfer process with an exposed silver chlorobromide emulsion and a developer having the following composition:

Component gJl 2.4-diamino-6-methylphcnol sulfate 5-l0 Tertiary butyl hydroquinonc 25 Na,S,O, 5H,O 60 NaOH 20 K011 20 Kl 0.6-] .6 Hydroxyelhyl cellulose 3-4.5 5: K,S0, 25-50 Water to make I liter The resulting print has a blue-black tone and a maximum density (D of l .64.

The above data indicate that a latex binder as described herein results in good tone and density when used as a binder for metal nuclei in a diffusion transfer process.

EXAMPLE 2 Poly( 2-chloroethyl methacrylateacrylic acid) Latex A coating solution containing colloidal palladium nuclei is prepared by adding Solution A to Solution B with vigorous stirring at 25 C.

Solution A PdCl,

10 N HCl Distilled water Solution 8 Latex containing 20% polymeric material from a monomeric mixture consisting of 2-chloroethyl methacrylate and acrylic acid in a ratio of 98:2 Distilled water Anionic Welling agent 0.00312 g. 0.003 ml.

l ml.

l ml.

The resulting solution is then coated on a polyethylene coated paper support to give a nuclei level of 0.035 mg./ft. and 39 mg./ft. solids. A silver bromoiodide gelatin emulsion coated on a paper support is exposed and the above receiver processed with a viscous developer as described below:

Water L360 g. Sodium carboxymcthyl cellulose I I7 g. Sodium Sulfitc Hi g. Sodium hydroxide 74.6 g. Sodium thiosull'atc l4.S g. Citric acid 38.5 g. Hydroquinone 52 g.

After removing the viscous developer from the print, the resulting image has a blue-black tone ove the whole H+D curve. D is L34, D,,,,-,, 0.97 and contrast 0.75.

EXAMPLE 3 In situ Preparation Part A Potassium chloraurate is dispersed in a physical mixture of 9 parts latex containing polymeric material prepared from a mixture consisting of 2-chloroethyl methacrylate and acrylic acid in a ratio of 98:2 and one part of a polymeric latex consisting of n-butyl acrylate and acrylic acid in a ratio of 9: l and coated on a polyethylene-coated paper support at 0. M4 mg./ft.

PartB Receiver D D,,,. Tone A 1.33 0.14 cold B 1.53 0.11 fairly cold A and B are overcoated with solutions of hypophosphorous acid rather than sodium borohydride and processed as above with similar results.

EXAMPLE 4 Latex coatings and Latex plus Gelatin coatings Palladium metal nuclei are precipitated in latex essentially as described in example 2. The resulting solution is then coated on a polyethylene coated paper support to give a palladium nuclei level of approximately 75 ug./ft. The nuclei are coated with varying amounts of gelatin, with the following influence on image tone.

A copoly(2-chloroethyl methacrylate-acrylic acid) 98:2 8 copoly(2 chloroethyl methacrylateacrylic acid) 96:4

As can be seen from the above examples, the addition of small amounts of a protein such as gelatin changes the image tone from cold to warm. Other proteins also have the same detrimental effect on tone in varying degree.

EXAMPLE 5 Latex Comparisons Coating compositions are prepared and processed as in example 2 except that various polymeric latexes are used. The polymers and results are as follows:

ratio by weight of monomeric Polymer Components mixture D. D,

2-chlorocthyl methacrylate 100 0.65 0.02 2-chlorocthyl mcthacrylatc & acrylic acid 98:2 1.36 0.16 2-chloroethyl mcthacrylatc & acrylic acid 96:4 1.12 0.13 2-chloroelhyl methacrylate &

methacrylic acid 96:4 1.06 0.02 2-chloroethyl methacrylatc & itaconic acid 98:2 078 0.15 2 chloroethyl methacrylate, 2-

chlorocthyl acrylate & acrylic acid 49:02:49 0.48 0.13 2-chlorocthyl methacrylate, 2-

chloroethyl acrylate & acrylic acid 24:02:74 0.61 0.15 2-chloroethyl methacrylate, 2

chloroethyl acrylate & methacrylic acid 74:24:2 no image 2-chloroethyl mcthacrylate, 2-

chlorocthyl acrylate k methacrylic acid 49:4912 0.45 0.13 2-chloroethyl mcthacrylate, 2-

chloroethyl acrylate & mcthacrylic acid 24:74:2 0.52 0.14 Z-chloroethyl melhacrylate, 2-

chloroethyl acrylate & itaconic acid 74:02:24 0.40 0.10 2-chloroethyl mcthacrylate, 2-

chloroethyl acrylate 8: itaconic acid 49:02 :49 0.35 0.10 2-chlorocthyl acrylate 100 0.62 0.10 Z-chloroethyl acrylate & acrylic acid 98:2 0.65 0.16 Z-chloroethyl acrylate & methacrylic acid 98:2 066 0.12 Ethyl methacrylatc 100 no image Ethylmcthacrylatc & acrylic acid 98:2 0.24 0.12

This invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variation and modifications can be effected within the spirit and scope of the invention.

We claim:

1. A substantially protein free receiving layer for use in a dilfusion transfer process comprising a colloid binder and silver precipitating agent, said colloid binder comprising at least percent, by weight, of a copolymer consisting essentially of 1) about 90 percent to about 98 percent, by weight, of at least one haloalkyl methacrylate in which said haloalkyl group contains one to 10 carbon atoms, with (2) about 2 percent to about 10 percent, by weight, of an ethylenically unsaturated polymerizable organic acid having three to six carbon atoms.

2. A substantially protein free receiving layer of claim 1 in which said precipitating agent is finely divided noble metal nuclei.

3. A receiving layer of claim 2 in which said noble metal is platinum.

4. A receiving layer of claim 2 in which said binder is copoly(2-chloroethyl methacrylate-itaconic acid).

5. A receiving layer of claim 2 which is coated over a polyethylene surface.

6. A receiving element comprising a support having thereon said receiving layer of claim 1.

7v A receiving element according to claim 6 in which said support is paper.

8. A receiving element according to claim 6 in which said precipitating agent comprises coated on said support in an amount of about 1 to about 200 g/ftF.

9. A receiving element according to claim 6 in which said binder is copoly(2-chloroethyl methacrylate-acrylic acid).

10. A photographic element comprising a support having thereon said receiving layer of claim 1 and having over aid layer an overcoat of a photographic silver halide emulsion.

11. A receiving element of claim 6 in which said silver precipitating agent is palladium nuclei.

12. A receiving element according to claim 6 in which said support is plastic film base.

13. A photographic element comprising an image in a substantially protein free receiving layer on a support, said image obtained by a diffusion transfer process, said receiving layer comprising a colloid binder and silver precipitating agent, said colloid binder comprising at least 90 percent, by weight, of a copolymer consisting essentially of (1) about 90 percent to about 98 percent, by weight, of at least one haloalkyl methacrylate in which said haloalkyl group contains one to 10 carbon atoms with (2) about 2 percent to about 10 percent, by weight, of an ethylenically unsaturated polymerizable organic acid having three to six carbon atoms.

14. A process of obtaining an image in a substantially protein free receiving layercomprising diffusing silver complex from undeveloped areas of an exposed and developing silver halide emulsion to said receiving layer, said receiving layer comprising a silver precipitating agent and a colloid binder comprising at least 90 percent, by weight, of a copolymer consisting essentially of (1) about 90 percent to about 98 percent, by weight, of at least one haloalkyl methacrylate in which said haloalkyl group contains one to 10 carbon atoms with (2) about 2 percent to about 10 percent, by weight, of an ethylenically unsaturated polymerizable organic acid having three to six carbon atoms.

15. A process of claim 14 in which said receiving layer comprises a silver precipitating agent.

16. A process of claim 14 in which the said polymer is a copolymer of 2-chloroethyl methacrylate with acrylic acid.

17. A process of claim 14 in which said silver halide emulsion is developed with a viscous processing composition. 

2. A substantially protein free receiving layer of claim 1 in which said precipitating agent is finely divided noble metal nuclei.
 3. A receiving layer of claim 2 in which said noble metal is platinum.
 4. A receiving layer of claim 2 in which said binder is copoly(2-chloroethyl methacrylate-itaconic acid).
 5. A receiving layer of claim 2 which is coated over a polyethylene surface.
 6. A receiving element comprising a support having thereon said receiving layer of claim
 1. 7. A receiving element according to claim 6 in which said support is paper.
 8. A receiving element according to claim 6 in which said precipitating agent comprises coated on said support in an amount of about 1 to about 200 Mu g./ft.2.
 9. A receiving element according to claim 6 in which said binder is copoly(2-chloroethyl methacrylate-acrylic acid).
 10. A photographic element comprising a support having thereon said receiving layer of claim 1 and having over said layer an overcoat of a photographic silver halide emulsion.
 11. A receiving element of claim 6 in which said silver precipitating agent is palladium nuclei.
 12. A receiving element according to claim 6 in which said support is plastic film base.
 13. A photographic element comprising an image in a substantially protein free receiving layer on a support, said image obtained by a diffusion transfer process, said receiving layer comprising a colloid binder and silver precipitating agent, said colloid binder comprising at least 90 percent, by weight, of a copolymer consisting essentially of (1) about 90 percent to about 98 percent, by weight, of at least one haloalkyl methacrylate in which said haloalkyl group contains one to 10 carbon atoms with (2) about 2 percent to about 10 percent, by weight, of an ethylenically unsaturated polymerizable organic acid having three to six carbon atoms.
 14. A process of obtaining an image in a substantially protein free receiving layer comprising diffusing silver complex from undeveloped areas of an exposed and developing silver halide emulsion to said receiving layer, said receiving layer comprising a silver precipitating agent and a colloid binder comprising at least 90 percent, by weight, of a copolymer consisting essentially of (1) about 90 percent to about 98 percent, by weight, of at least one haloalkyl methacrylate in which said haloalkyl group contains one to 10 carbon atoms with (2) about 2 percent to about 10 percent, by weight, of an ethylenically unsaturated polymerizable organic acid having three to six carbon atoms.
 15. A process of claim 14 in which said receiving layer comprises a silver precipitating agent.
 16. A process of claim 14 in which the said polymer is a copolymer of 2-chloroethyl methacrylate with acrylic acid.
 17. A process of claim 14 in which said silver halide emulsion is developed with a viscous processing composition. 